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Updated: Jun 25, 2025
Author Spotlight: Decoding Mitochondrial Aging
Published on: June 30, 2023
Visualization of cristae and mtDNA interactions via STED nanoscopy using a low saturation power probe
Wei Ren1, Xichuan Ge2, Meiqi Li3
1Department of Biomedical Engineering, National Biomedical Imaging Center, College of Future Technology, Peking University, Beijing, 100871, China.
Abstract:
Mitochondria are crucial organelles closely associated with cellular metabolism and function. Mitochondrial DNA (mtDNA) encodes a variety of transcripts and proteins essential for cellular function. However, the interaction between the inner membrane (IM) and mtDNA remains elusive due to the limitations in spatiotemporal resolution offered by conventional microscopy and the absence of suitable in vivo probes specifically targeting the IM. Here, we have developed a novel fluorescence probe called HBmito Crimson, characterized by exceptional photostability, fluorogenicity within lipid membranes, and low saturation power. We successfully achieved over 500 frames of low-power stimulated emission depletion microscopy (STED) imaging to visualize the IM dynamics, with a spatial resolution of 40 nm. By utilizing dual-color imaging of the IM and mtDNA, it has been uncovered that mtDNA tends to habitat at mitochondrial tips or branch points, exhibiting an overall spatially uniform distribution. Notably, the dynamics of mitochondria are intricately associated with the positioning of mtDNA, and fusion consistently occurs in close proximity to mtDNA to minimize pressure during cristae remodeling. In healthy cells, >66% of the mitochondria are Class III (i.e., mitochondria >5 μm or with >12 cristae), while it dropped to <18% in ferroptosis. Mitochondrial dynamics, orchestrated by cristae remodeling, foster the even distribution of mtDNA. Conversely, in conditions of apoptosis and ferroptosis where the cristae structure is compromised, mtDNA distribution becomes irregular. These findings, achieved with unprecedented spatiotemporal resolution, reveal the intricate interplay between cristae and mtDNA and provide insights into the driving forces behind mtDNA distribution.
Insights
Researchers visualized mitochondrial DNA (mtDNA) dynamics using a novel probe and STED microscopy. They discovered mtDNA positioning influences mitochondrial fusion and cristae remodeling, crucial for cellular health and disrupted in ferroptosis.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Molecular Imaging
Background:
- Mitochondria are vital organelles regulating cellular metabolism and function.
- Mitochondrial DNA (mtDNA) encodes essential transcripts and proteins.
- The interaction between the inner mitochondrial membrane (IM) and mtDNA is poorly understood due to imaging limitations.
Purpose of the Study:
- To develop a novel in vivo probe for visualizing the mitochondrial inner membrane (IM).
- To investigate the spatiotemporal relationship between IM dynamics and mtDNA distribution.
- To understand the role of mitochondrial dynamics and cristae remodeling in mtDNA organization.
Main Methods:
- Development of a novel, photostable fluorescence probe (HBmito Crimson) for lipid membranes.
- High-resolution, low-power stimulated emission depletion (STED) microscopy (40 nm spatial resolution).
- Dual-color imaging combining IM visualization with mtDNA localization.
Main Results:
- HBmito Crimson enabled visualization of IM dynamics with unprecedented spatiotemporal resolution.
- mtDNA is predominantly located at mitochondrial tips and branch points, with overall uniform distribution in healthy cells.
- Mitochondrial fusion occurs near mtDNA, suggesting a role in minimizing pressure during cristae remodeling.
- Healthy cells exhibit Class III mitochondria (>5 μm or >12 cristae), which significantly decreases in ferroptosis (<18%).
- Mitochondrial dynamics and cristae remodeling promote even mtDNA distribution.
- Apoptosis and ferroptosis compromise cristae structure, leading to irregular mtDNA distribution.
Conclusions:
- The study reveals an intricate interplay between mitochondrial cristae and mtDNA distribution.
- Mitochondrial dynamics, driven by cristae remodeling, are essential for maintaining uniform mtDNA organization.
- Compromised cristae structure in ferroptosis and apoptosis leads to aberrant mtDNA distribution, highlighting potential disease mechanisms.
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